Maybe Jerry Brown was more right about marijuana than folks gave him credit for -- at least if a new study on pot has merit.

You may recall that California’s governor, appearing on NBC’s “Meet the Press” in March, had this to say about marijuana legalization: “How many people can get stoned and still have a great state or a great nation? The world’s pretty dangerous, very competitive. I think we need to stay alert, if not 24 hours a day, more than some of the potheads might be able to put together.”

Published in the Journal of Neuroscience, the study examined 40 participants, ages 18 to 25: 20 who said they were casual pot smokers and 20 who didn’t smoke. Of the pot smokers, half said they smoked about four days a week (an average of about 11 joints), while half smoked fewer than six joints a week.

And what did brains scans show? In two areas associated with emotion, motivation and reward processing, the scans showed pronounced differences from the nonsmokers’ brains. And the more marijuana the subject smoked, the more pronounced the changes.

At last! Scientific evidence of what everyone who has ever been around a stoner already knows.

But this is 21st century America, land of the free, home of the brave -- and of the people who don’t trust science anymore. Climate change? A hoax. “Cosmos”? Why not equal time for creationists? Bigfoot? I saw one yesterday.

So don’t expect this study to change anyone’s mind. Marijuana supporters quickly pounced: The study’s sample is too small; 11 joints a week is not “casual” use; it’s just evil big government at work -- because the National Institute on Drug Abuse, a federal agency, helped pay for the study.

And the other view? Here’s Dr. Hans Breiter of the Northwestern University Feinberg School of Medicine and Massachusetts General Hospital, and a study author: “What we think we are seeing here is a very early indication of what becomes a problem later on with prolonged use, [things like lack of focus and impaired judgment].”

Personally, I don’t have a dog in this fight. I somehow escaped the ’60s without partaking of either demon rum or demon pot (my application for sainthood is pending). Yet I know plenty of folks who weren’t so pure and yet are fully functioning, useful members of society (and then, some are lawyers.)

In other words, I still think it’s too early to tell just how bad -- or relatively harmless -- marijuana is. And for what it’s worth, I also think this: I’m willing to bet you won’t find that many parents of teenage boys and girls (even parents who smoked pot themselves) among those pushing for marijuana legalization.

Still, for those pining for a bigger study, it seems to me we’re already conducting one, given the new freedoms in Colorado and Washington state: You’re not just a Coloradoan or Washingtonian, you’re a lab rat!

In the meantime, though, I also happen to agree with our esteemed governor. Given the choice, I think it makes sense -- this one is for you, Nancy Reagan -- to “just say no.”

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